According to an embodiment in the prior art, a starter comprises a launcher, which is mobile in translation and rotated by an electric motor. At its end, the launcher comprises a pinion which can engage with a toothed crown which is integral in rotation with (i.e., non-rotatably connected to) the crankshaft of the internal combustion engine. In order to start an internal combustion engine, it is necessary to increase its speed of rotation to approximately 200 rpm. According to the mode of use known in the prior art, the starter is used when the engine is at a standstill.
FIG. 1, which relates to the prior art, illustrates schematically an electric starter of this type, in its position of rest with the engine at a standstill. When a contact 110 is closed, power is supplied to a solenoid 120. This solenoid comprises a coil 121 known as a pull-in coil, and a coil 122 known as a hold-in coil. The power supplied to the solenoid 120 gives rise to the translation of a plunger 130. During this translation, the plunger 130 drives a pinion 160 of a launcher in translation by means of a fork, which is also known as a lever 161, which pinion 160 then engages with a crown 190 which is connected in rotation (i.e., non-rotatably) to the crankshaft of the engine. Thus, the plunger 130 and the pinion 160 are integral in translation according to this embodiment in the prior art. At the end of the course of the plunger 130, by means of a contact plate 131, the plunger establishes electrical contact between an armature 151 of an electric motor 150, and a positive terminal 101 of the vehicle battery. The electric motor 150 then rotates the pinion 160 of the launcher (as the electric motor 150 is non-rotatably connected to the pinion 160), which drives the crown 190 and launches the rotation of the internal combustion engine. In this position, with the contact plate 131 establishing the power circuit between a vehicle battery 100 and the armature of 151 the electric motor 150, the pull-in coil 121 is short-circuited, and the plunger is retained in position by the effect of the hold-in coil 122. When the contact 110 is open, the magnetic forces generated by the effect of the hold-in coil 122 and the pull-in coil 121. This is due to the fact that the direction of the current in the pull-in coil is inverted. In addition, when the contact 110 is open, a compression spring 132 thrusts the plunger 130 back, thus opening the contact previously established by the contact plate 131, and separating the pinion 160 from the crown 190. The connection in rotation (i.e., non-rotatable connection) of the pinion 160 to the electric motor 150 is provided by means of a free wheel mechanism 165, such that the pinion 160 is separated from the motor 150 when it is driven by the crown 190. This device according to the prior art gives satisfaction for the initial starting of the engine, when the engine is started by actuating the contact key, or by pressing a starter button.
The lever which is supported against a housing of the starter comprises play, known as the cut-off play 161, in order to allow the plate 131 to move away from the terminals in the case of an abnormality of the pinion blocked in the crown. The lever against the housing provides a pivot connection and translation perpendicular to the pivot.
Many vehicles are equipped with an automatic stop-restarting device known as “stop and go”. According to this device, the internal combustion engine is cut-off automatically as soon as the vehicle is at a standstill, i.e. the running of the engine at idling speed is not maintained when the vehicle is at a standstill. When the driver is preparing to set off once more, for example when he presses the clutch, the engine is automatically restarted. This functioning mode makes it possible to save fuel in the phases where it is not necessary to have the engine running. Although this restarting is rapid, it is not instantaneous. In addition, according to the prior art, the fuel supply to the engine is also cut-off when the vehicle is in the engine brake situation, i.e. when the driver is not pressing the vehicle accelerator. According to the prior art, the cut-off of the supply to the thermal engine is continued until the engine reaches a predetermined speed corresponding for example to 1500 rpm, thus making it possible to maintain the supply to the engine in order to keep it running at least at idling speed, even if the said engine is not participating in the propulsion of the vehicle. In fact, it is considered that the internal combustion engine can no longer start autonomously in all situations, when its speed drops below a certain threshold of approximately 300 rpm. However, the starter according to the prior art, the functioning of which has previously been described, needs the engine to be at a standstill in order to begin to function, as a result of the balancing phase during which the starter cannot put its pinion into the crown. Thus, when a vehicle is equipped with a restarter device, it is necessary to detect that the thermal engine has actually stopped. The solutions according to the prior art thus lead to complex control of the system for stopping and restarting of the engine.
For example, the engine is not stopped, but is kept idling, for as long as the driver is exerting pressure on the clutch, even if the gearbox is in neutral and the vehicle is stopped. Since the restarting is not instantaneous, the driver tends to maintain pressure on the clutch when he anticipates a short-term stoppage, thus depriving himself of fuel savings.